As is well known, a nonvolatile memory is able to continuously record data after the supplied power is interrupted. Consequently, the nonvolatile memory is widely used in a variety of electronic products.
Generally, the nonvolatile memory may be implemented by floating gate transistors or anti-fuse transistors. By using a proper controlling mechanism, hot carriers may be injected into or ejected from the floating gate of the floating gate transistor. Consequently, the nonvolatile memory composed of floating gate transistors may be used as a multi-time programming memory (also referred as a MTP memory).
Moreover, the storage state of the anti-fuse transistor is determined according to the ruptured state of the gate oxide layer of the anti-fuse transistor. After the gate oxide layer is ruptured, the gate oxide layer fails to be recovered. Consequently, the nonvolatile memory composed of anti-fuse transistors may be used as a one time programming memory (also referred as an OTP memory).
The nonvolatile memory composed of anti-fuse transistors is disclosed in for example U.S. Pat. Nos. 7,402,855 and 6,791,891. However, the one time programming memory fails to be repeatedly programmed and lacks the characteristics of the multi-time programming memory.